J.W. Performance® - Pro-Comp Automatic Transmission Assembly

00 reviews / Item # 585397513
$2,686.50 - $5,265.00
In Stock - Ships within 24 hrs
1974 Chevy Impala
Fits Following Model(s):
  • THM400 Transmission
  • Not recommended for street use
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    Product Details

    J.W. Performance Transmission Components

    Chevy Impala THM400 Transmission 1974, Pro-Comp Automatic Transmission Assembly by J.W. Performance®. Bell housing: Ready for Ultra-Bell. These transmissions build on the same features as the Ultra-Comp Series but add: Pro-Tree Aluminum Valve Bodies and many other upgrades, for extreme levels of horsepower. Double neutral, and 1st and 2nd gear trans-brake options available. The workhorse of all 3 speeds! Originally released in 1964, the TH400 has proven again and again to be an ideal racing automatic. From Hot Rods to Pro-Mods, the TH400 can be built in many combinations. You can choose from any of standard units. Horsepower ratings are approximates, other factors contribute to transmission horsepower ratings, i.e. vehicle weight, torque, driving habits, etc.

    Notes: Not recommended for street use

    J.W. Performance


    • Built using the most technologically advanced equipment
    • Made from highly durable materials to last for a long time
    • Made to deliver utmost combination of performance and reliability

    Valve Body Tech
    There are many options available when choosing a valve body for your TH400. When using a true "automatic" valve body you must have a constant minimum source of 14in/lbs of vacuum going to the modulator at all times. This especially holds true in Turbo-Charged or Super-Charged engine applications that run little to no vacuum. If you have one of these engines strongly suggest running a Full Manual valve body which will eliminate all need for vacuum, or at the very least utilizing a vacuum pump. Offer "automatic" valve bodies in 2 variations: Manual/ Auto which is a firm shift that can be manually shifted, and will hold manual 1st and 2nd gears, great for a hot rod application. Also offered is the "Fully Automatic" HD shift which removes the delay out of the shift, ideally suited for RV or towing type applications.

    J.W. Performance Transmission, Inc. is a leading manufacturer of high performance automatic transmissions and components for drag and off road racers, street and strip enthusiasts, and more. Headquartered in Rockledge, Florida, J.W. Performance® manufactures thousands of quality transmissions and related parts ranging from flexplates to bellhousings. The company pioneered over 250 products since 1976. Many of its innovative solutions remain the industry standard and are widely used by professional racers in the United States and abroad.

    Warranty Information

    J.W. Performance provides a limited warranty against defective parts and workmanship. The following is a list of the specific length of warranty of time for each part:

    1 Year: 7″-10″ Ultra-Comp Converter, Gear Set, Complete Planetary

    90 Day: Ultra-Bell, Ultra-Case, Ultra-Pump, Valve Body, Tailhousing, Input Shaft, Solenoid, 11″ and 12″ Converter, 10″ Sportsman Converter, The Wheel, Deep Pan, Sprag, Stator, New Transmission, Refreshed Transmission.

    30 Day: Shifter

    J.W. Performance assumes no liability in the use of any product. If an item is suspected of being defective, it must be returned within 10 days for inspection after J.W. Performance has given authorization. After inspection of the part, J.W. Performance Transmissions will advise what/if an allowance is due. Any disassembly of the product done by anyone other than J.W. Performance will void any and all warranties/guarantees. It is recommended that you keep a copy of your sales receipt. J.W. Performance Express Limited Warranty does not cover any misuse, abuse, unauthorized repairs, unauthorized modifications, failure due to improper installation, or failure due to improper maintenance. Freight handling, removal, and reinstallation charges for replacement parts is not covered. Normal wear is not covered.

    Magnuson-Moss Warranty Act:
    Legally, a vehicle manufacturer cannot void the warranty on a vehicle due to an aftermarket part unless they can prove that the aftermarket part caused or contributed to the failure in the vehicle (per the Magnuson Moss Warranty Act (15 U.S.C. 2302(C)) Learn More

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